From c5b9b7d03a37b807b212c29a9bdf7afc837c5423 Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Fri, 14 Jul 2017 23:34:55 -0400
Subject: Lex and parse parentheses

---
 __tests__/lexer.test.js  | 28 ++++++++++++++++++++++++++++
 __tests__/parser.test.js | 30 ++++++++++++++++++++++++++++++
 src/lexer.js             |  2 ++
 src/parser.js            |  8 ++++++++
 4 files changed, 68 insertions(+)

diff --git a/__tests__/lexer.test.js b/__tests__/lexer.test.js
index e9115a1..38c880e 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -88,4 +88,32 @@ describe('lex', () => {
       ])
     })
   })
+
+  describe('lexes parentheses', () => {
+    it('(1d6)d6', () => {
+      expect(lex('(1d6)d6')).toEqual([
+        { type: '(' },
+        { type: 'constant', value: 1 },
+        { type: 'd' },
+        { type: 'constant', value: 6 },
+        { type: ')' },
+        { type: 'd' },
+        { type: 'constant', value: 6 }
+      ])
+    })
+
+    it('2d(6+3)d4', () => {
+      expect(lex('2d(6+3)d4')).toEqual([
+        { type: 'constant', value: 2 },
+        { type: 'd' },
+        { type: '(' },
+        { type: 'constant', value: 6 },
+        { type: '+' },
+        { type: 'constant', value: 3 },
+        { type: ')' },
+        { type: 'd' },
+        { type: 'constant', value: 4 }
+      ])
+    })
+  })
 })
diff --git a/__tests__/parser.test.js b/__tests__/parser.test.js
index 6fe296c..a741007 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -72,4 +72,34 @@ describe('parse', () => {
       }
     })
   })
+
+  describe('parsing parentheses', () => {
+    test('(1d6)d6', () => {
+      expect(parse('(1d6)d6')).toEqual({
+        type: 'd',
+        left: {
+          type: 'd',
+          left: { type: 'constant', value: 1 },
+          right: { type: 'constant', value: 6 }
+        },
+        right: { type: 'constant', value: 6 },
+      })
+    })
+
+    test('2d(6+3)d4', () => {
+      expect(parse('2d(6+3)d4')).toEqual({
+        type: 'd',
+        left: { type: 'constant', value: 2 },
+        right: {
+          type: 'd',
+          left: {
+            type: 'add',
+            left: { type: 'constant', value: 6 },
+            right: { type: 'constant', value: 3 }
+          },
+          right: { type: 'constant', value: 4 }
+        },
+      })
+    })
+  })
 })
diff --git a/src/lexer.js b/src/lexer.js
index fd347c6..f559816 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -22,6 +22,8 @@ newValueLexeme('constant', '\\d+', Number)
 newLexemeType('d', 'd')
 newLexemeType('+', '\\+')
 newLexemeType('-', '-')
+newLexemeType('(', '\\(')
+newLexemeType(')', '\\)')
 newSkippableLexeme('whitespace', '\\s+')
 
 const lex = (expressionString) => {
diff --git a/src/parser.js b/src/parser.js
index 6c39c77..9f2c6ac 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -16,6 +16,14 @@ newSymbol('constant', function() {
   return { type: 'constant', value: this.value }
 })
 
+newSymbol('(', function(parser) {
+  const value = parser.expression(1)
+  parser.match(')')
+  return value
+})
+
+newSymbol(')')
+
 newSymbol('d', null, 30, (left, parser) => {
   return {
     type: 'd',
-- 
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